1. Field of the Invention
The present invention relates to method and apparatus for controlling fuel injection in an internal combustion engine, and more particularly to method and apparatus for controlling fuel injection in an internal combustion engine including an in-cylinder fuel injection valve for injecting a fuel into a cylinder and a manifold fuel injection valve for injecting a fuel into an intake manifold.
2. Description of the Background Art
A technique to provide a pressure-lowering pipe between a fuel supply pipe for supplying a fuel to a fuel injection valve and a drain pipe in an internal combustion engine including an in-cylinder fuel injection valve for injecting the fuel into a cylinder has been known (for example, see Japanese Patent Laying-Open Nos. 2-119669, 7-103048, 2001-342876, and 2002-4985). In such an internal combustion engine, if the pressure inside the in-cylinder fuel injection valve is raised due to volume expansion of the fuel present therein as a result of heat from the internal combustion engine when it is stopped after warm-up, the pressure inside the in-cylinder fuel injection valve is lowered by opening the pressure-lowering pipe.
In the internal combustion engine including the in-cylinder fuel injection valve for injecting the fuel into the cylinder and the manifold fuel injection valve for injecting the fuel into the intake manifold, when the internal combustion engine is stopped while the fuel is being injected from the manifold fuel injection valve, the internal combustion engine stops with some fuel injected from the manifold fuel injection valve being adhered to the intake manifold.
The fuel adhered to the intake manifold may evaporate while the internal combustion engine is not running, and may be exhausted to the outside through an intake system. In addition, the adhered fuel that has evaporated while the internal combustion engine is not running may be exhausted to the outside through an exhaust system during cranking for re-starting the internal combustion engine. If the internal combustion engine is stopped with the fuel being adhered to the intake manifold, emission may be deteriorated.